Dyno results with K&N 63 Series and Fabspeed exhaust (mufflers)

I dynoed my 02' Carrera with the addition of a K&N 63 series intake and a Fabspeed exhaust. History: My baseline dyno earlier this summer was on a Dynojet 248C run at 97 degrees with a peak of 270.1 hp at 6200 rpms run with the lid closed (lid open, it only dynoed in the 230-250's). The low peak is probably due to not using a fan to get proper airflow into the engine through the rear spoiler as it would have while driving on the road. I joined in with the local GTO club in their Dyno Day event today. A couple of the participants were mentioning that they were dynoing about 20 hp lower than they did when tuning a week ago, but I can't verify this since I did not baseline on this same dyno. My dyno today was on a different dyno of the same type in similar test conditions: 93 degrees temperature also on a Dynojet 248C. Runs were made with the lid open (I don't think lid up or down will effect the dyno with the 63 series like it does with the stock intake). The result was an improvement of exactly 22 hp to 292.1 hp. We did not have a good tach signal for the dyno, so there is no torque curve. It appears to have about the same power peak of 6200 rpms. My guess is that a fan will be necesssary to get enough airflow to match what the rear spoiler scoops in at speed to get it to continue to pull power to a 6800 rpm peak. Hopefully this will answer some of the speculation questions about these mods since these are real world results. I don't know if the exhaust added 10 hp or the intake added 19 hp, but I can verify I picked up at least 22 hp from these mods together and I am satisfied for the $850 I paid for both. If you look carefully, you can see the car picked up 15-25 rwhp everywhere from 4400 rpms (about 73 mph) up to the limiter.

Sweet. I imagine I'll see something similar with my GHL's.

Good to know.. What's the 63 series K&N?

Unless you ran the car in the EXACT same conditions in the EXACT same dyno at the EXACT same time adding each mod both individually and stepped then you will NEVER know if they worked to the numbers you think. But it does feel good to see quasi numbers that make you feel like you got your $$$ worth.

This is actually as close it is could get to accuracy. You can't dyno with and without mods at the same time. If you were to make a dyno run with the stock airbox and then switch immediately on the dyno, you won't get the same results as after 2 days of driving under a variety of conditions so the ECU has adapted to the changes. You will most likely lose power with the mods. Some of this has to do with the changes that came along with rediness monitors and OBDii. I tried to do with intakes on my G35 Coupe and it actually lost HP with the performance intake on back to back runs. The ECU requires time to learn the changes and adapt the maps. This is part of the reason why some people don't get CEL lights initially, but get it 50-100 miles when the ECU is learning the changes. Dyno types were identical. Both were calibrated for stardard temperature and humidity in the morning of the events. The graphs are different because each used a different version of Winpep software. Data logging was the same sample rate. Although there was a 3 hour difference between run times during the day, humidity was within 5% and there was only a 4 degree temperature difference (no surprise with Texas in the summer). Baseline SAE correction factor was 1.04 and modded correction factor was 1.03.

At WOT, there is no learning needed by the ECU. Changes are immediate. Also, if dyno's accurately account for differences in temperature, humiidy, etc, why mention what temperature you ran it in? Seems to me, if the calculation was accurate, you could run in 200F temperatures and still get the same adjusted power figures. However, the calculations are NEVER correct and a dyno should be used as an estimated indication of HP and nothing more.

Don't be so hard on Carrera. Yes dynos vary from day to day but you have to have something to compare and the 248c seems to be pretty consistent over time. I'd be pretty happy with the results even if they are a little off. Carrera, what gear were you in? You really should do 996s in 5th which is as close to 1:1 as you are going to get. You appear to be in a lower gear. I guess being consistent is the most important anyway. Do you have the raw files? If not you should get them. You can download the display software from Dynojet. That would allow you to overlay your different runs. One thing that is suspicious. Your first run has a big power loss when your cams shift at 6200. Your second run doesn't seem to have the issue. I doubt that has anything to do with your mods so I would wonder why. Jim

Both dynos were run in 4th gear. I did not plan for the baseline to be done in 4th, they just did it from habit. Yes, 5th is closer to 1.0 than 4th. I intentionally had the second dyno done in 4th to match the first. I do have the Winpep files for both sets of runs. The second is logged slightly different in that there was no rpm signal. It is logged by MPH instead. Fortunately, it is not too hard to correlate the speed data to rpms. I'll try to overlay them and see how it ends up. Keep in mind that the raw data files will not have the corrections applied to them since it shows the uncorrected data. This means there will be even more of a spread between the 2 runs than you see here since there is a greater SAE correction factor on the baseline runs. As a couple other notes. Not only were both dynos Dynojet 248C's, but they were also both above ground dynos. Both dynoes were located in the back of each shop with the rollers backed up against a back support wall. If you look at the 2 plots, the smoothing is obviously different; but there is still the same dip in the second dyno around the same rpms. It still drops a good 5 hp like the first one. I still believe that this has to do with airflow problems on the dyno as no fans were used to help provide airflow to the engine on any of the runs. I agree there there are some fluxuations from dyno to dyno and day to day, but this will account for a very small amount of error (1-2%). This difference should be minimized from the SAE corrected results.

Would you like to explain what the Alpha values are and what they do? You should give a call to GIAC, Powerchip or Jim Wolf Technology if you don't know or understand what they are.

You make a mod, you reset computer. At WOT, ECU is looking at his MAF reading primarily, not O2 sensors, fuel trims, etc. Timing, etc, responds to MAF reading, engine and intake temps immediately. Like I said, no learning curve for WOT.

I understand there is a correction for MAF 'scaling' - in other words how the MAF output varies with flow. Some can be dead accurate at low flow but get wider of the mark at high flow, others the exact opposite. As far as I'm aware, this is calculated by the DME from the lambda corrections required at varying flows and finally extrapolated to WOT and other higher throtle openings once enough data has been acquired. This also explains why some K&N users don't get a CEL for many miles. Ian W

At WOT, the O2 sensor readings are not even a factor. Learning is for closed loop operation only (other than knock). The learning consists of finding the proper balance for the fuel trim for startup and cruising. Again, this has nothing to do with performance at WOT. Disconnect your o2 sensors at WOT and your performance will be unchanged.

Thanks for placing this here! I am still on the fence about the K&N upgrade based upon what I am reading but it sounds like you got your moneys worth out of these upgrades!

Are you sure? I'm no expert but don't your O2s control air/fuel. Wouldn't that be a primary area of adjustment when adding intake and exhaust mods?

What 1999Porsche911 stated is correct. At WOT O2 sensors do not play a role. Fueling is based strictly on a predetermined map. O2 sensors are used during closed loop operation to achieve optimum fuel efficiency/emissions characteristics.

It wasn't even the same Dyno. How is this going to show you anything? We all know they are calibrated differently. Can you go back to the one you did the baseline on?

So if WOT is based on a predetermined fuel map, then anyone with a more efficient intake and/or exhaust is running lean? Now that would be something worth checking on the dyno.

Not at all. The mapping will accommodate increased fuel if the computer sees that there is additional air....just like it accommodates for cooler air (more fuel), different timing (more fuel), etc. On the opposite end...if the Maf reads less air, the fuel will be reduced at WOT regardless of the maximum mapping.

It is correct that o2 sensors only work in closed loop: constant speed and light acceleration. At WOT the car does run on the fuel and timing based maps. There is no O2 sensor in a production automobile that will react quickly enough for this condition. At this point it is a "best guess." The actual maps are fixed when in open loop, but that is not the end of the story. That is except for a couple changes that came along with self-learning an OBDii to improve this: these are the Alpha (base registers). These are set in the self learning part of the ECU. Alphas are applied to the maps to modify the readings for measured running conditions. These are some of the things that are set in OBDii drive cycles. Alphas are set by accerating, crusing and decelerating at certain speeds and taking measurements off engine sensors. They are tied to the rediness monitors (part of OBDii). Once they are set, if the sensor inputs are out of range of the monitors then the ECU will re-enter self-learning mode. If it can't adjust the Alphas to correct the readings, it will start tripping codes or the rediness monitors will fail to set (showing a "not ready" or "fault" condition).

What does this have to do with a dyno run at WOT. FACT: Make a change to the airflow, air temperature, coolant temperature or altitude and the effect is immediate. Not learned, but immediate. This is why some people like to put a fan on the engine or intake or radiator so the dyno results will be higher. Do you think they make a few dozen runs so the ECU can learn that there is a fan blowing?

So with a K&N, the CEL is because the computer is having troubling settling the variables and not that you have a serious problem. If the computer is reset then will it learn it correctly? Is it a function of bad driving style during learning or the initial conditions being not reset?

It has EVERYTHING to do with a dyno run at WOT. If you make a change to an intake that alters how the accuracy of the MAF is maintained with increasing airflow (like the K&N does with no flow straighteners for example) then the ECU will re-learn whilst in closed-loop mode. One thing it learns is how the MAF accuracy varies with airflow and these corrections are extrapolated to keep the MAF in calibration when out of the closed loop area. You are right that it does not learn when running 'open loop' but if the extrapolated closed-loop learning mode has not been fully completed then the lambda values at WOT will not be what they will eventually be once the learning mode is completed. hence why cars pick up power over many miles after a mod is made. So you are correct in one way - at WOT the car is running on map only with no intervention from the O2 sensors - but wrong in another. At WOT the cars run from a MODIFIED map with the miodifications being made during learning mode and extrapolated up to WOT. If you dyno before the car has re-learnt, it will run from the already-stored modified map. If there is 5% more airflow or 10degrees less temp or whatever, it will instantly use the values in the current map appropriate to the new airflow and temp. However these will not necessarily be optimum settings. What will happen over time is trhat this map will be modified and the car will eventually run on those more accurate settings. Ian W

That's a damn fair point. Moreover, read this from Car and Driver.

Well not sure how long it takes the computer to relearn new air intake, but my CEL has come on twice in 3 days with the K&N CAI.

Sounds all good and techy, but the fact remains that the computer does NOT calibrate the MAF in anyway. ANY and ALL changes to the MAF readings (like increased or decreased air flow) immediately effects the amount of fuel to the engine at WOT. The MAF is nothing more than a current producer that reports to the computer. At WOT, there is a specific current and that is what the computer uses for fueling. The learning you are referring to is for closed loop ONLY. The CEL's you are getting are from closed loop ONLY. When changes in current from the MAF occur, it can take a few miles for the adjustments made by the O2 sensors to effect the LTFT. And this occurs ONLY in closed loop, not at WOT. This is the learning process. At WOT, the computer does not even look at the fuel trims so they have no negative or positive effect on performance.

You you mean closed loop, is that why my CEL came on twice while idle at a red light?

The computer goes closed loop after a few minutes of warmup. Idle is the primary time for O2 sensor generated CEL's.

I'm staying out of this because it's not my area of expertise but I have to say it's a hell of a lot more interesting than posuer or income threads. 1999, my understanding of the ecu maps much closer to Ian's. Where are you getting your info? I'm not saying you're wrong because I don't know. Are you as sure that there are no "learning" adjustments at WOT as you seem to be? Jim

I think our disagreement is between open and closed loop. Other than adjustments due to knock, there is no learning by the ECU in open loop. All learning is done in closed loop. At WOT, the ECU no longer cares what the O2 sensors or fuel trim are saying and takes it's instructions from the current from the MAF, including intake temperature and air volume. It also continues to read coolant temperature and will adjust timing accordingly. Ever notice how much faster your car is when it is cold outside? MAF is sending more current (lower intake temp reading) to the ECU. This is telling the computer that there is nore dense air coming into the engine and it had better increase the amount of fuel to keep the A/F ratio as demanded by the map. Does your car perfom better as soon as you start driving it, or does it have to wait to "learn" that it is getting colder air? The orginal comment made by 02 Carrera was that a change in airflow will not give you the same results at WOT as it will 2 day later. This is simply not the case with a properly functioning MAF. I really don't know what else I can say. A fact is a fact. If you are getting more air and the MAF is reporting this increase, you will get the appropriate amount of fuel increase and your power will increase immediately. Not much to learn there.